Massey Ferguson A.31.18 – Transmission/Hydraulic Control Unit: External Hydraulic Valve 3 Issue

Electrical or operational fault within the third external hydraulic remote valve circuit. The system logs this when it detects a connection problem on the hydraulic valve, a current level error, or a 'fast decay error' (solenoid valve remaining open longer than intended or failing to close fast enough). It can also be triggered by an open circuit or a short circuit in the wiring to Solenoid Valve 3.

• 5710SL
• 5711SL
• 5712SL
• 5713SL
• T4
• 4707
• 4708
• 4709
• 4710
• 5608
• 5609
• 5610
• 5611
• 5612
• 5613
• 7614
• 7615
• 7616
• 7618
• 7619
• 7620
• 7622
• 7624
• 7626
• 7714
• 7715
• 7715S
• 7716
• 7716S
• 7718
• 7718S
• 7719
• 7720
• 7720S
• 7722
• 7722S
• 7724
• 7724S
• 7726
• 7726S

1. 1

   Check UTTO hydraulic fluid level and condition (look for dark, burnt, or milky fluid indicating water contamination)

2. 2

   Inspect the hydraulic filter for heavy contamination and verify it has been changed within the 250–500 hour service interval

3. 3

   Inspect the wiring harness and electrical connector at External Hydraulic Valve 3 for corrosion, frayed wires, open circuits, or shorts to ground

4. 4

   Perform a system pressure test using a hydraulic pressure gauge at the quick couplers to verify if pressure is within spec (e.g., not dropping below 2200 psi)

1. 1

   Relieve System Pressure

   Turn off the tractor and actuate the hydraulic levers to relieve any residual pressure in the system before working on the valves.

2. 2

   Service the Fluid/Filter

   If the diagnostic checks revealed degraded fluid or a clogged filter, drain the hydraulic fluid, replace the hydraulic filter with an OEM unit, and refill with fresh UTTO fluid.

3. 3

   Repair Wiring

   If the wiring harness to Valve 3 is damaged, repair the broken wires or replace the connector pigtail to resolve the open/short circuit.

4. 4

   Replace the Solenoid Valve

   If the wiring is intact but the valve fails to operate correctly (e.g., internal position sensor fault or magnet output stage fault), the External Hydraulic Valve 3 (solenoid spool valve) must be removed and replaced.

5. 5

   Clear Codes

   Connect a compatible Massey Ferguson diagnostic tool or interface device to the tractor to clear the 0A.31.18 DTC and recalibrate the transmission/hydraulic system if necessary.